1. Field of the Invention
The present invention relates to the field of copy protection of computer software and more particularly to embedding a copy protection circuit within a microprocessor chip.
2. Prior Art
In order to prohibit illegal copying of computer software, various prior art techniques are available to provide protection from such illegal copying. Although various techniques are available to protect the copying of computer software, it is difficult to grasp the realities of software utilization in the personal computer environment. Therefore, some of the more sophisticated techniques do not lend themselves to such personal computer environment. Most software vendors will provide some means of copy protection on their products which are sold on floppy disks. Typically, the copy protection is in the software itself. However, in this instance, the user cannot readily make backup copies or copy the program from a floppy disk to a hard disk. In some instances, special copy tools are needed to provide for such legal copying. In addition, it is not possible to effect a perfect copy protection since various copy tools can be used to make copies or disable the intended protection.
One of the more common methods of providing copy protection of computer software is by applying some treatment to the floppy disk to disable copying to any other source. Generally some special code is written onto the outside of the normal track of the floppy disk and this code is not copied properly when ordinary copy commands are utilized. In this instance, a special copy tool is required. However in such instances the copy tools must be very sophisticated in order that such tools cannot readily be exploited by the copy pirate. Such tools cannot prohibit illegal use of software.
In the personal computer environment, most application software are sold to the user on floppy disks. However, to facilitate the usage of such application programs, most users require the program to be copied onto the hard disk of their personal computer system. It is impossible or highly inconvenient to install protected software on the floppy disk to permit only such copying onto a hard disk. Therefore, in most instances a copy tool is required to make such a copy, but again, such tools can be readily used to illegally copy the software. Although it may be possible to derive such highly complex protection mechanisms, the more complex the protection, the more time is required for checking the routine of the software. Further, once the program is copied onto a hard disk, it is almost impossible to prevent copying of the program from the hard disk onto another medium.
It is appreciated then that what is required is a simple computer software copy protection mechanism wherein illegal copying of this software is prohibited, but ordinary copy commands can be utilized to permit legal copying without the use of external copy tools.